To use a mobile phone to access a packet switched domain of the 3rd generation mobile telecommunications technology (3G, 3rd-generation) and a general packet radio service (GPRS, General Packet Radio Service) network through radio access technology, a user needs to configure an access point name (APN, Access Point Name) for the mobile phone first to initiate a packet data protocol (PDP, Packet Data Protocol) context activation process. According to APN information carried in an activation request message, a serving GPRS support node (SGSN, Serving GPRS Support Node) queries IP address information in a domain name system (DNS, Domain name system) server to determine which gateway GPRS support node (GGSN, Gateway GPRS Support Node) is creating a PDP context, thereby achieving access to different external packet data networks (PDN, Packet Data Network).
Currently, mobile operators have been establishing an increasing number of virtual private networks (VPN, Virtual Private Network). As regards one user, after obtaining a service list (service list) of the user, a GGSN may obtain an APN and a VPN that are associated with each service by querying the service list. As the mobile operators have been developing new diversified services, and each service is associated with an APN, the mobile operators need to create more APNs. For each new APN, it is required to update configuration parameters of a corresponding device in a system, such as: user subscription data in a home location register (HLR, Home Location Register), domain name system resolution configuration parameters in a DNS, and routing configuration information in a GGSN. This work undoubtedly aggravates the complexity and the cost of network management for the mobile operators. In addition, a user needs to change the APN configuration of the mobile phone if the user accesses different services, which increases operation complexity for the user.
To address the foregoing problems, a multiservice (Multi Service) APN solution based on content resolving is developed. A user may subscribe to several services (service), and allow a mobile operator to plan an APN for activating the service when the user accesses the network. A GGSN uses that APN to obtain subscription service information of the user. Therefore, the user may access various packet data networks by using the same APN.
In the prior art, a GGSN may obtain user subscription information in three modes: a remote authentication dial in user service (RADIUS, Remote Authentication Dial In User Service) mode, a policy and charging rules function (PCRF, Policy and Charging Rules Function) mode and a GGSN mode. In the three modes, the user subscription information is obtained in a similar way. The following takes the RADIUS mode as an example for description. The GGSN uses the APN contained in the activation request message (request APN) to perform authentication in an authentication, authorization and accounting (AAA, Authentication Authorization Accounting) server of a mobile operator and obtain subscription service information of the user. Then, the GGSN reassigns an IP address for a service PDP context by using different assignment methods based on different assignment manners of different IP addresses, and activates the service PDP context, so that the user may carry a data packet by using the assigned EP address to access a PDN network. However, in the prior art, when activating a service PDP context, the GGSN reassigns an IP address to the service PDP context by using different assignment methods based on different assignment manners of different IP addresses. Because there are many IP address assignment manners, IP address reassignment becomes complicated, and performance of a GGSN is affected. The IP address assignment manners include GGSN local assignment, AAA assignment, carrying a static address by a user, dynamic host configuration protocol (DHCP, Dynamic Host Configuration Protocol) assignment, and the like.